1. Field
Embodiments of the present invention generally relate to apparatus and methods for processing semiconductor substrates. Particularly, embodiments of the present invention relate to processing a semiconductor substrate in a rapid thermal processing chamber.
2. Description of the Related Art
Rapid thermal processing (RTP) is a process for annealing substrates during semiconductor processing. During RTP, a substrate is generally supported by a supporting device near the edge region and rotated as the substrate is heated by a heat source. Thermal radiation is generally used to rapidly heat a substrate in a controlled environment to a maximum temperature of up to about 1350° C. The maximum temperature is maintained for a specific amount of time ranging from less than one second to several minutes depending on the process. The substrate is then cooled to room temperature for further processing. High intensity tungsten halogen lamps are commonly used as the source of heat radiation. The substrate may be provided additional heat by a heated susceptor conductively coupled to the substrate.
In semiconductor fabrication, RTP may be performed as part of various processes, such as thermal oxidation. An RTP chamber is usually part of a cluster tool where the RTP chamber shares a factory interface and a substrate transfer robot with various other processing chambers. Since semiconductor substrates are generally processed with a device side facing up, an RTP chamber also has the configuration of positioning the substrates with the device side facing up in order to share the substrate transfer devices with other processing chambers. With the substrate positioned device side facing up, RTP chambers usually have a heating source positioned below the substrate so that the substrate can be heated from the backside to achieve uniform heating. The heating source is sized at least as large as the substrate to cover the entire substrate. Thus, traditional RTP chambers generally have a substrate support assembly for supporting and rotating a substrate above a heating source disposed under a chamber body and actuators of the substrate support surrounding the heating source. As a result, traditional RTP chambers have large substrate support actuators and a large footprint.
FIG. 1 schematically illustrates a traditional RTP chamber 100. The RTP chamber 100 includes a heating assembly 106 disposed outside a chamber body 102 under a transparent chamber bottom 103 for dispensing infrared radiation. The heating assembly 106 includes a plurality of radiant heating sources 104 disposed in a frame 108. The plurality of radiant heating sources 104 may be any suitable energy sources, such as heating lamps, laser diodes, light emitting diodes. A substrate support 110 positions a substrate 114 over the heating assembly 106. The substrate support 110 is mounted over an actuator assembly 112 disposed around the heating assembly 106. The actuator assembly 112 is configured to vertically move and rotate the substrate support 110 during processing. In order to heat the substrate 114 in a substantially uniform manner, the frame 108 is usually larger than the substrate 114 to distribute the plurality of lamps 104 across the entire substrate 114. The frame 108 usually also includes cooling structures that further increases the size. As a result, the actuator assembly 112 which surrounds the heating assembly 106 and the chamber body 102 which encloses the substrate support 110 are much larger than the substrate 114 being processed. As shown in FIG. 1, the diameter D of the chamber body 102 is much larger than the diameter d of the substrate 114.
Therefore, there is a need for a RTP chamber with reduced chamber size and footprint.